Before you choose a cruise, decide what you're looking for: an all-night-party-till-you-drop weekend? A sunny place to bask like a lizard? Exotic ports?
Then consider cost: from as low as about $100 a day to $600 a day.
Don't be shy about calling around to different travel agents, especially to cruise-only agencies; you'll see their ads in newspaper travel sections or in the Yellow Pages under "cruises."
Ask whether the agent has traveled on the cruise line, or even the ship, you're considering.
An experienced agent should also be able to tell you what kind of crowd you're likely to find aboard -- families, young singles, senior citizens.
Cost: The type of cabin -- inside or outside -- can make a big difference in price, so if it doesn't make much difference to you, that's one place you can save money.
Going solo: For a person traveling alone, the cabin price is high. But if you're willing to gamble, you can get a bargain.
Through a share program, you can get the double-occupancy rate for a cabin, if you're willing to be matched with a roommate of the same gender and age group. You may get a roommate; you may end up with the cabin on your own.
You won't know whether you have a roommate until you reach the ship, but unless you draw the "cruiser from Hell" as your bunkie, it seems a win-win proposition to me: If you are matched, you have somebody to talk to. If you aren't matched, you get a bargain deal on a cabin by yourself.
Tipping: If you don't drink or gamble very much, tipping could be your single biggest expense.
At least three times -- in a pre-trip brochure, in a card in my cabin, in the cruise director's talk -- Royal Caribbean explained what's a standard tip for your room steward, head waiter, waiter and busboy, and how to bestow it in a way that Miss Manners would approve (on the last evening, in an envelope. They even supply the envelopes).
Figure on total tips of about $35 per passenger for a four-day cruise; if you spend a lot on bar drinks or wine, you'll need to add more for waiters, wine stewards, etc.
Dress: If you like dressing up, the formal night can be as formal as you like. But you won't be out of place in whatever clothes you'd wear to a nice restaurant. Daytime is casual.
For minimal motion, choose a cabin located midship. I saw lots of passengers wearing anti-nausea patches behind their ears. Those were available from the ship's doctor, but you should check with your own doctor about seasickness medication.